The first season originally aired from September 24, 2013, to May 13, 2014, while the second season aired from September 23, 2014, to May 12, 2015. A third season premiered on September 29, 2015, concluding on May 17, 2016, and the fourth season premiered on September 20, 2016, and concluded on May 16, 2017. A fifth season of Agents of S.H.I.E.L.D. premiered on December 1, 2017 and is scheduled to conclude on May 18, 2018. After starting the first season with high ratings but mixed reviews, the ratings began to drop while reviews improved. This led to much lower but more consistent ratings, as well as more consistently positive reviews in the subsequent seasons.

Contents

The first season sees S.H.I.E.L.D. Agent Phil Coulson putting together a small team of S.H.I.E.L.D. agents to handle strange new cases.[2] They investigate Project Centipede and its leader, "The Clairvoyant", eventually uncovering that the organization is backed by Hydra, which has infiltrated S.H.I.E.L.D. In the second season, following the destruction of S.H.I.E.L.D., now-Director Coulson and his team look to restore trust from the government and public while dealing with Hydra, a faction of anti-superhuman S.H.I.E.L.D. agents, and the newly revealed Inhumans (who possess special abilities).[3][4]

During the third season, Coulson begins a secret mission to assemble the Secret Warriors, a team of Inhumans,[5][6] as Hydra restores its ancient Inhuman leader Hive to power.[7] After the defeat of Hive and with Hydra destroyed, S.H.I.E.L.D. is made a legitimate organization once again with the signing of the Sokovia Accords. In the fourth season, Coulson returns to being a field agent, due to the world believing he is dead, and is tasked with tracking down more enhanced people including Robbie Reyes / Ghost Rider. In addition, Agent Leo Fitz and Holden Radcliffe complete their work on the Life Model Decoy project as well as the development of the Framework.[8] The fifth season sees Coulson and members of his team mysteriously abducted to a space station run by the Kree in the year 2091, where they must try and save the remnants of humanity while figuring out how to get home.[9]

Clark Gregg as Phil Coulson:
A S.H.I.E.L.D. agent who oversees many of the division's field operations.[10] In April 2013, Gregg agreed to join the series after hearing Whedon's explanation for Coulson's resurrection, following the character's death in The Avengers, which he called "fascinating" and "true to the world of the comics and mythology". On whether the resurrected Coulson would be the same as before he died, Gregg said the character had to have changed in some way, but he may not understand how much he has changed.[11] Gregg said he approached Coulson's promotion to Director of S.H.I.E.L.D. as being his dream job, which at the same time forced the character to adopt a more level-headed attitude, like that of Nick Fury.[12]

Ming-Na Wen as Melinda May:
A S.H.I.E.L.D. ace pilot and weapons expert, nicknamed "the Cavalry".[13] Joss Whedon had the character, who was originally listed with the name Agent Althea Rice on casting sheets,[14] "rolling around in his head" for a long time. Wen was given some backstory for the character to prepare, but was not told how she gained her reputation;[15] with May's past revealed in "Melinda", Wen called it "devastating ... To have learned what she had to do, for the good of the many ... I can understand why it would traumatize her so much and cause her to retreat."[16] Wen called May "unconventionally maternal",[17] and found that it is her relationship with Coulson rather than any feelings about S.H.I.E.L.D. that make her stay in the organization.[18]

Brett Dalton as Grant Ward and Hive:
Ward is a Hydra agent who poses as a S.H.I.E.L.D. black ops specialist.[19][20] From the conception of the series it was decided that he would be a traitor, with Jed Whedon explaining that they wanted to have "infiltration based on betrayal" on a small scale to represent the same thing happening on a massive scale, and to make the Hydra reveal more personal for the characters.[21][22] Following the death of his Hydra superior, John Garrett, Dalton explained that he felt that Ward was always loyal to Garrett rather than Hydra, and so without Garrett would become more of a wildcard,[23] eventually accepting his position as an antagonist to S.H.I.E.L.D.[24] He is killed by Coulson in season three[25] and his body is possessed by the ancient Inhuman Hive.[7] Dalton returned to the series in its fourth season to portray Ward in the Framework, the virtual reality world created by Holden Radcliffe, where he is Johnson's boyfriend.[26]Austin Lyon portrays a young Ward.[27]

Chloe Bennet as Daisy "Skye" Johnson / Quake:
An Inhumanhacktivist and S.H.I.E.L.D. recruit who eventually becomes an agent with the ability to sense vibrations and create earthquakes.[4][14] The character of Skye was always intended to be the MCU version of Johnson, with Tancharoen noting that the reveal would have consequences for the character's relationships, especially with Coulson.[28] Bennet felt that the character was someone who would wear her heart on her sleeve, but she also has some control over her emotions.[29] Wen noted that the character evolves from being "anti-establishment into suddenly being someone who wants to create an establishment that would help" the Inhumans.[17] During the third season, the character no longer goes by "Skye", and by the end is known as "Quake" to the public.[30][31]

Iain De Caestecker as Leo Fitz:
An agent of S.H.I.E.L.D. who specializes in engineering, especially weapons technology.[14][32] De Caestecker, in describing the character, said that "He's quite passionate about what he does ... [but] he doesn't really understand emotions as much".[33] Fitz has a lot of interaction with Simmons in the series, with De Caestecker explaining that "they've got this kind of weird chemistry together, and they just kind of fit each other in a very weird way."[34] The character receives brain injuries at the end of the first season, with the writers researching brain trauma with doctors and experts before approaching it in the series. De Caestecker did his own research as well, feeling it is "something that should never be trivialized. It's a real and serious thing to a lot of people, brain trauma, so we just have to constantly be respectful towards it."[35]

Elizabeth Henstridge as Jemma Simmons:
A S.H.I.E.L.D. biochemist who specializes in life sciences (both human and alien).[14][32] Henstridge described her character as "intelligent and focused and curious...she's got a wonderful relationship with Fitz. They kind of bounce off each other."[36] As Fitz and Simmons begin to spend time apart during the series, Henstridge noted that it "brings a whole new dynamic just to them as characters in discovering what it's like to have to be independent" since they have been near inseparable since first meeting.[37] On the harsher side of Simmons seen later in the second season, Henstridge noted that the character has "always been very mathematical in a way".[32] After Simmons is trapped on the planet Maveth for six months, she becomes "profoundly different", with Henstridge saying, "she doesn't just completely change. But she's been through so much. She's hardened. She's had to face things that she never would've imagined [by] herself without Fitz, so she's ... stronger and kind of damaged."[38]

Nick Blood as Lance Hunter:
A mercenary before agreeing to join S.H.I.E.L.D.[39] On his character joining the cast in the second season, Blood explained "Lance doesn't really care that much of what people think of him....He doesn't bow down to the etiquette of the S.H.I.E.L.D. hierarchy."[40] He later elaborated that the character feels very independent, so would probably not want to admit no longer feeling like an outsider. Also, "he doesn't have too much respect for authority and titles...if Coulson does something he respects, that's all good. If he doesn't, he's going to say something." On Hunter's on-again, off-again relationship with Bobbi Morse, Blood said, "there is a lot of truth in it of those relationships you have where it's kind of, 'can't live with each other, can't kill each other'".[41]

Adrianne Palicki as Bobbi Morse:
Hunter's ex-wife and an agent of S.H.I.E.L.D. who spent time undercover within Hydra.[42] Palicki was approached by the showrunners specifically for the part during season two, and at first hesitated to take the role given that she likely could not play another MCU character if she did. Palicki already had martial arts and gun training, but had to learn to use the character's signature arnis sticks; she noted similarities between Morse's fighting style and that of Scarlett Johansson's Black Widow from the MCU films.[43] Bell said of the character, "she and Hunter have been keeping secrets from one another, evidently for years" and something about her is that she seems to be more loyal to an idea than anything else, so what may seem in the short term as a betrayal by her is usually for what she sees as the greater good.[44]

Henry Simmons as Alphonso "Mack" MacKenzie:
A S.H.I.E.L.D. mechanic with a distrust of the alien and superhuman.[45] On the different dynamic that a mechanic brings to the S.H.I.E.L.D. team, Simmons felt that his character would not have to deal with the same stress as the other agents, and that Mack is more worried about contributing in his own way and getting his job done away from the field.[46] About Mack's stance on violence, Simmons confirmed that Mack does not like violence, but will do "what he has to do."[47] Mack reveals in the third season, "It's not something I talk about but ... I rely on my faith", implying that he is a Christian.[48] This was seen by Dee Hogan of The Mary Sue as "a refreshingly positive portrayal of people of faith, as Mack demonstrates the quiet confidence and love rather than the aggression and bigotry that's so often associated with it."[49]

Luke Mitchell as Lincoln Campbell:
An Inhuman with the ability to manipulate electrical charges.[50] The character was introduced because the series already featured "a guy with no eyes" and "a woman who now is covered in thorns" but, like the X-Men, there are also Inhumans who are "just attractive people with powers", and so Campbell represents them in the series. On casting Mitchell, Bell said "Luke just really impressed us ... [he] had a nice quality, and we felt he might be a good person to sort of usher Skye into this other world."[51] Campbell dies in the third season finale,[31] making him the "Fallen Agent" that the series had been teasing for the entire second half of that season.[52][53] The decision was made because the producers did not want "a body count show, but it is a real world with real stakes."[54]

Natalia Cordova-Buckley as Elena "Yo-Yo" Rodriguez:
A Colombian Inhuman who can move at a super speed for a beat of her heart, before returning to the point she started moving from. She reluctantly joins S.H.I.E.L.D. and becomes a part of the Secret Warriors, eventually growing close to Mack who gives her the nickname "Yo-Yo".[58][59] When first portraying the character, Cordova-Buckley smiled whenever Rodriguez was about to use her abilities, to show an adrenaline rush and the feeling of having such power. After positive fan responses to this, the actress morphed this trait into a more mischievous personality for the character.[60]

In August 2012, ABC ordered a pilot for a series called S.H.I.E.L.D. to be written and directed by Joss Whedon, with Jed Whedon and Maurissa Tancharoen also writing.[68][69] Disney CEO Bob Iger greenlit the series after watching the Marvel One-Shot short film Item 47.[70] In April 2013, ABC announced that the series would be titled Marvel's Agents of S.H.I.E.L.D.,[2] and it was officially picked up for a full season of 22 episodes in May 2013.[70][71] Jed Whedon, Tancharoen, and Jeffrey Bell act as the series' showrunners,[68] with Bell joining the show to help the inexperienced former pair with hiring crew members and "navigating the politics of studios and networks", saying, "My job is to help them learn how to do that, to steer the ship while they learn." Joss Whedon assisted them before he started work on Avengers: Age of Ultron.[22]

The series was renewed for a second season in May 2014,[72] a third in May 2015,[73] a fourth in March 2016,[74] and a fifth in May 2017.[75] In September 2016, discussing the eventual end of the series, Tancharoen said, "You always just forge ahead. Until someone tells us to stop, we will continue to move forward." Jed Whedon added, "There are always ideas in the back of your mind for how you'd wrap it up when they say, 'That's it guys,' but we're not there just yet."[76] By May 2017, Bell noted they had "a sense of how we'd like the show to end when it ends. We just need to know when that time is coming so we can build to it properly." Jed Whedon continued, "Our goal is to know ahead of time, because we would love to land the story in a way that's satisfying".[77] In January 2018, ABC Entertainment president Channing Dungey was optimistic about the series receiving a renewal for a sixth season.[78]

The idea of [Coulson] as the long-suffering bureaucrat who deals with Tony Stark's insufferability is delightful and hits the core of something I'm also writing about all the time—the little guy versus the big faceless organization....and that's what Clark Gregg embodies: the Everyman.

Bell explained that he, Jed Whedon, and Tancharoen supervise all of the series' creative decisions, often consulting with Loeb. When the showrunners are writing the series, one person can write a script while the other two break stories, so that a story can be broken every few weeks. If the executive producers sign off on a story, a member of the series' writers room then produces an outline, gets notes on it from the showrunners, writes a full script, gets notes on it from ABC and the production crew, and then goes to set to produce the episode.[22]

In January 2013, Joss Whedon deflected any direct influences from other series, such as the efforts of Fox Mulder and Dana Scully in The X-Files, and explained that while the show would involve people with powers and the spectacle of science-fiction storytelling, it would focus on "the peripheral people...the people on the edges of the grand adventures."[80] As the series began to introduce more powered individuals, Bell noted that audiences "seem to respond to powered people on the show and while it's not going to take over and become what the show's about, as a texture and flavor of the stories, we really enjoy that."[81] Jed Whedon stated that the series would continue to emphasize the general public's response to powered people, saying, "The dynamic in the world has changed. There was one person with powers, and then by The Avengers there were maybe six total ... now they're much more prevalent, so there's reaction from the public based on that."[82]

On the balance between creating new material and drawing from existing mythology, Bell noted that telling stories that can entertain both Marvel fans and non-Marvel fans is challenging, and that for the series they try to add nods to the MCU films or the comics in a way that works well on its own for all viewers, but could also mean more for a fan.[83] On where the series can draw from the comics, Jed Whedon explained that there are areas of the comics that the series is not allowed to go to, and that ultimately they only use the comics for inspiration in generating their own story. Tancharoen elaborated that, "We're always going to be inspired and influenced by the comics, but of course on the show, we'll always be doing our spin to it."[84] About comparisons between the scope of the series and that of the films, Bell said that ABC and Marvel had been very generous with the series' budget, and that the production could not complain for a network series, but that it was nothing compared to the films or even series like Game of Thrones. He explained that the series does attempt to create "Marvel moments" as best it can, but pointed out that some of the more memorable moments from the films are smaller, character moments—something that works really well on television—so the series strives for those when it cannot afford more scope and scale.[83] Jed Whedon elaborated that they look at a sequence and try to keep only what is required to tell the story, so "If a monster is landing on a car, instead of showing the whole monster leaping through the skyline, we want to be in the car with the character having that experience."[21]

(L to R) Jed Whedon, Maurissa Tancharoen, and Jeffrey Bell, the showrunners of Agents of S.H.I.E.L.D.

In September 2015, Bell looked back on the first two seasons and talked about the challenges of and changes in the series. He noted the negative reception from fans concerning the low number of recognizable characters like Coulson, but pointed out that fans seemed to have grown to like the series' original characters as they had been developed over time. He explained that with the increasing number of characters and complex relationships in the series, having different pairings and building new emotional relationships was important, and stated that "whether it's a quiet moment or in action, we [hope to] deepen the audience's love and concern, and hopes for these characters."[85] A year later he reiterated the producer's intention to create a tradition moving forward of "finding new combinations and new conflicts" between different sets of characters, given "a lot of procedurals [see] the same people doing the same thing for five years and the character don't evolve or change at all."[82]

The producers and writers initially formed a general plan for the show through the end of a third season, after reading the screenplays for upcoming MCU films.[86] In May 2016, Chloe Bennet likened the end of the third season to "the end of the first book of S.H.I.E.L.D. ... the end of something bigger and the beginning of a whole new tone for the show."[87] She elaborated that "the storylines that we started at the beginning of season 1 really wrapped up at the end of season 3. We've had some major losses of people who have been with us on the show since season 1. From the table read to the first day on set, there's definitely a new energy of the show" moving forward.[88] The series was moved to the later timeslot of 10 pm for the fourth season. Jed Whedon said the writers hoped to "skew a little darker because of" this change, with Loeb adding that "It absolutely offers opportunities. I don't know that it changes things all that dramatically [though]. I mean, at the end of the day, Marvel is always going to make shows that run somewhere between PG-13 and PG-16. We're not going to be making Deadpool anytime soon on [ABC]."[82] Marvel "had a long talk with ABC about what can we get away with, so to speak" in the new timeslot, which led to the inclusion of Ghost Rider in the season over one of Marvel's Netflix series, because Marvel felt "that this character was right to tell [darker and more violent] stories right now" and having him on S.H.I.E.L.D. aided that because "it was so unexpected". Loeb hoped that the combination of the later timeslot and the introduction of Ghost Rider would lead to some viewers who had stopped watching the series over the previous seasons giving it another chance.[89]

In May 2017, ahead of the fifth season renewal, Jed Whedon said the writers were not sure what would happen in the season, and that it would be "by the seat of our pants."[90] While beginning to write the final episode of season 5 at the end of February 2018, the writers were planning for it to be able to serve as both a season and series finale, with some elements that could be adjusted based on whether the series was renewed for a sixth season or not. Whedon added, "we're ready for if this is the end. We're definitely going to make it rewarding either way."[91]

In October 2012, a casting sheet for five lead roles was sent out.[14] At the New York Comic Con, Joss Whedon, Kevin Feige, and Clark Gregg announced that Gregg would be reprising his role as agent Phil Coulson from Iron Man, Iron Man 2, Thor, The Avengers, and the Marvel One-Shots in the pilot,[10] and would "headline" the series.[92] Actress Ming-Na Wen was cast as Melinda May.[13] The next month, Elizabeth Henstridge and Iain De Caestecker were cast as Jemma Simmons and Leo Fitz, respectively,[32] while newcomer Brett Dalton was cast as Grant Ward.[93] In December, Chloe Bennet was chosen out of more than 400 actresses to play Skye, the sixth and final regular for the first season;[94][95] the character is revealed in the second season to be Daisy Johnson, and no longer goes by "Skye" starting with the third.[30]

All season two principal cast members returned for the third season,[5] with Simmons and Mitchell joining them, promoted from their recurring roles.[50][101] In October 2015, the Inhuman Hive was introduced; for the second part of season three, he possesses the corpse of Grant Ward, again portrayed by Brett Dalton.[7] Also introduced were Natalia Cordova-Buckley and John Hannah, recurring as Elena "Yo-Yo" Rodriguez and Holden Radcliffe, respectively.[58][55] Blood and Palicki left the main cast following the season three episode "Parting Shot", to star in the then-planned spin-off show Marvel's Most Wanted.[102] Dalton and Mitchell also left following the deaths of their characters in the third-season finale.[54]

Gregg, Wen, Bennet, De Caestecker, Henstridge, and Simmons returned for the fourth and fifth seasons.[8][103] They were joined by Hannah in the fourth,[56] with Cordova-Buckley once again recurring as Rodriguez in the season,[104] before being promoted to a series regular for the fifth season.[59] Dalton returned as a guest during the third pod of the fourth season,[26] while Blood made his return to the series during the fifth season.[105]

Betsy Heimann was the costume designer for the pilot, but left the series due to film commitments. Assistant costume designer Ann Foley took over for subsequent episodes, and worked closely with Tancharoen to create "very strong, different characters" whose "looks evolve along with the show."[106] Foley also brought on concept artists Phillip Boutte Jr. and Josh Shaw to assist with the design process.[107][108] Foley watched every MCU film, paying special attention to The Avengers, and was also inspired by such films as Skyfall and Mission Impossible: Ghost Protocol.[106] In October 2016, Foley said that she was specifically following the aesthetic of Captain America: The Winter Soldier, "So any costume has to fit inside that world we've established and has to fit that tactical look."[109] On the variety of costumes created for each character, Foley preferred to have set pieces in the characters' "closets", as "it's not a fashion show ... a guy like Ward isn't going to have twenty jackets in his closet. He is going to have one that he uses all of the time."[108]

After reading each script, Foley would do her own research, before discussing the look of the episode with the writers.[110] She then studies the comics, general fashion, and history to get a look that is recognizable to fans, but fits into the more realistic world of the series.[107] Costumes are either custom made or bought, and the actors are brought in for fittings before filming. This process was often challenging due to the series' eight-day-per-episode schedule.[110] Foley stated that all costumes take a similar amount of time to create, whether they are based on the comics or not.[111] Marvel CCO Joe Quesada is involved in the approval process when costuming preexisting characters,[108] including Daisy Johnson's Quake costume that is introduced in the third season. The Quake costume incorporates elements from the comic version of the character, and was intended to show that Quake "could easily be part of the Avengers".[112][113] Foley took steps to differentiate the Quake costume from Scarlett Johansson's Black Widow costumes from the films, but was "flattered" by comparisons made between them. Foley was also adamant about not sexualising characters such as Quake to show that "these characters don't have to be sexualised, that they're powerful, strong women", and so avoided "a lot of cleavage, you don't see high heels. It's about practicality."[109]

The costumes go through a natural evolution in the series. There is a shift at the end of the first season to a darker look, and all the characters have "definitely grown up" during the second season. In the third season there is another shift, "from the ragtag group of soldiers and scientists to [a] more precise militaristic outfit".[112] This change is also reflected in the series' color palette, going from "a much lighter tone, much more patterns" in the first season to having "stripped away a bit of color" by the third.[109] Despite this increasing darkness in the costumes, Foley intended to define each character as they are introduced and to have them always be recognizable and identifiable.[108] With the start of the fourth season, Foley said that "each season definitely has its own feel and this season will be no different. I think that you're going to see some subtle differences in the costumes of the characters"; she felt like Fitz and Simmons, in particular, had become "more adult looking", while all the cast had "a pretty specific ... civilian look" that would become more prominent as S.H.I.E.L.D. is re-legitimized and becomes more public.[113] Foley left the series after the thirteenth episode of the fourth season, to work on a television adaptation of Altered Carbon,[114] and was replaced with Amanda Riley. Riley used her previous experience recreating costumes to "blend in" with Foley's established look.[115]

Foley returned for the first two episodes of the fifth season, before handing over to Whitney Galitz, who had assisted Foley on the previous few seasons, and Christann Chanell.[116]

The series' props department is led by Scott Bauer. The pilot introduces the Incapacitating Cartridge Emitting Railgun or ICER tranquilizer weapons often used by the agents, with Joss Whedon having Bauer design "sci-fi" looking guns including a large rifle-like weapon. The series further portrayal of the ICERs was more subtle, with Bauer using airsoft guns that are safe to shoot others with over a small distance. ICER-specific muzzle flashes are then added by the visual effects department. Bauer reused the ICER rifle prop when making Mack's "Shotgun Ax", which appears in later seasons. The terrigen crystals that unlock Inhuman abilities in the series are 3D-printed from solid resin and then altered with extra details.[117] Additional practical effects and props are created by Legacy Effects, who also work on the MCU films,[111][118] notably creating Daisy Johnson's gauntlets for the third season.[111]Prosthetic makeup for the series is designed in conjunction with Glenn Hetrick of Optic Nerve Studios. Hetrick began work on the series with the second season, to create Raina's Inhuman look,[119] and returned for the third season to design and create the more "unique"-looking Inhumans such as Lash.[120]

The title sequence for the series' 100th episode, "The Real Deal", featured a montage of all title cards used throughout the series

The third season introduces a new title sequence for the series, replacing the one that appeared in the first two seasons.[121] The title sequence in "4,722 Hours" is drastically different from the design introduced for the third season, with the series' title in the episode's typeface silently fading onto the screen over the back drop of the planet Simmons is stranded on.[122][123] The fourth season sees new series title cards for the Ghost Rider and LMD pods,[124][125] and an Agents of S.H.I.E.L.D. title card for the Agents of Hydra pod that changes to say Agents of Hydra for episodes primarily set in the Framework.[126][127] The Ghost Rider graphic is used again for the fourth-season finale.[128] For the fifth season, the opening of "Orientation" is reminiscent of the sequence for "4,722 Hours", forgoing the title card and having the typeface silently fading onto the screen.[129] The subsequent episodes of season five feature a title card inspired by the opening sequence of "Orientation" - the series name against a backdrop of Earth - with episodes through "Past Life" featuring a destroyed Earth,[130] while the subsequent episodes feature a fully-formed Earth.[citation needed]

FuseFX serves as the lead visual effects vendor for Agents of S.H.I.E.L.D.,[139] with additional work by Pixomondo, Cosa, Greenhaus GFX, Lion VFX, and Synaptic.[132] The series sees an average of 80 to 150 visual effects shots per episodes,[138] with 10 to 12 days to work on the effects for one episode once background plates have been received from filming.[139] This equates to approximately 2000 visual effects shots per season.[132] Mark Kolpack serves as visual effects supervisor for the series.[140] David Altenau was the in-house supervisor at FuseFX for "Pilot" through episode eight, with Kevin Lingenfelser taking over for subsequent episodes.[141] VFX producer Andrea D'Amico joined the team at FuseFX to work on the series in December 2015.[142] Two separate production management and creative teams were established to work on the show, and producers, compositors and various artists were able to alternate episodes. This was important because most of the episodes had to be worked on concurrently, either two or three at a time.[141] Typical effects for the series include the creation of character-driving effects animation, photo-realistic vehicles, CG set extensions, pyrotechnics, and atmospheric effects.[139] Some assets, such as a Quinjet and Helicarrier, are shared from Industrial Light & Magic, though "those models are generally super heavy and dense with data" and need to be made "HD friendly or simply manageable to work in [a] TV schedule."[138]

Bear McCreary confirmed that he would compose music for the series in July 2013.[143] Unlike on some of his previous scores, ABC and Marvel allowed McCreary to work with a full symphonic orchestra,[144] typically featuring 50 or 70 players,[145] with over 90 for "important" episodes.[146] Complex synthesizer programming was also used, to give the score "a modern edge".[147] Since Agents of S.H.I.E.L.D. was the first MCU television series, McCreary felt there was "a sense that it had to connect" to the consistent orchestra sound of the films, but viewed through a television lens.[146] McCreary composes on average 30 minutes of music per episode.[148] Creating the main theme for the series, which McCreary also saw as Coulson's theme, was a process which took a lot of collaboration with the executive producers, who wanted a specific sound—"something big, that...belonged in the Marvel Cinematic Universe" but also "intimate because these aren't superheroes, these are regular people." McCreary had to work harder to make the theme heard, given that the show does not have a traditional title sequence.[144] By the third and fourth seasons, McCreary noted "the score became a little more intense and more electronically driven... [E]lectronics really moved to the forefront as we got into more stories about Inhumans and the digital world our characters inhabit. But the orchestra is always our foundation."[146]

In September 2014, McCreary announced that there were plans for an Agents of S.H.I.E.L.D. soundtrack,[149] which was released digitally a year later by Marvel Music on September 4, 2015, and on CD on October 9. Featuring music from the first two seasons, the soundtrack was written and produced by McCreary and Steven Kaplan, with the album produced by Joe Augustine with McCreary.[150][151]

All music composed by Bear McCreary.[151] Notes next to each track indicate which episode(s) it was featured in.[148]

We're part of the Marvel Cinematic Universe, and so...we pitch our stuff to Kevin Feige and his movie group to see if there's something we can tie into, to see if they're okay about us using a character, or a weapon[, etc.]

—Executive producer Jeffrey Bell in September 2014, explaining the process of working in with the MCU.[22]

In July 2013, Jed Whedon said the series would work in tandem with the Marvel films, both past and upcoming, to weave in between the films, and to "try to make them more rewarding on both ends."[152] He explained that each Marvel project is intended to stand alone first before there is any interweaving, and noted that the series has to work with the film division and be aware of their plans so as not to interfere when introducing someone or something to the universe.[153] Bell elaborated that this was preferable so that people who do not watch the films can still follow the series, and vice versa. He stated that "ABC and Marvel both want the series to be able to make sense on its own", but that it was beneficial for the films to have the series fill in any "gaps" for them, due to having to be "big" and moving "quickly through a lot of huge pieces", unlike television which has time to deal with more nuances.[85]

In January 2016, Joss Whedon noted that this process "unfortunately just means the TV show gets, you know, leftovers." He stated that, for example, the series' creative team initially wanted to use Loki's scepter from The Avengers but were unable due to Whedon's plans for it in Age of Ultron.[154] On how their ability to connect with the films changed over the life of the series, Jed Whedon said, "The rule when we started was we couldn't say anything about spies, we couldn't say anything about Hydra, we couldn't have any A.I. or robots or anything like that, because all of that was coming in movies that year or the year after. Since then, they've blown those doors wide open." He added, "We have relatively free rein [in what the series can introduce and connect to]; we just can't go anywhere that [the films are] going. They know their stories so much further out than we do, which is good for us to tee up things that we know are coming to them or avoid things that they want to be special on the big screen. As long as we are not covering bases that they're going to cover, we haven't been told "no" that much". As an example, Whedon noted the fourth season's Framework storyline as "something that's pretty significant in our world, but is also a little eddy in the river that doesn't affect anything else because it's an alternate universe. So those kinds of stories help us go big without sending ripples through the whole MCU."[77]

The series mimics the films' post credits scenes with 'end tags', starting with the episode "0-8-4" which features a Samuel L. Jackson cameo. Bell explained, "Sometimes it'll be funny, sometimes it'll be a mythology thing ... or an extra little reveal about" the episode.[83] The end tag for "End of the Beginning" is a "directly lifted" scene from Captain America: The Winter Soldier.[155]

The episode "T.A.H.I.T.I." introduces the Kree alien race to the MCU, members of which play a significant role in Guardians of the Galaxy.[165][166] This begins a storyline that recurs throughout the series, and introduces Inhumans to the MCU,[4] with Jed Whedon saying that it was something "in the works" for a long time, as Marvel Studios had plans for an Inhumans film, and this would be "one of the first instances where we get to start planting the seeds on the show before the film."[167] The third season introduces the concept of the Secret Warriors, with new Inhuman characters inspired by the comic of the same name,[6][168] while also retconning the history of Hydra in the MCU, tying it into the Inhumans storyline.[169] Gregg noted in January 2016 that the "writer and director [of the Inhumans film] will have free rein to do what they want to do with the Inhumans, but hopefully there'll be some way that our Inhumans connect to that."[170] When the film was removed from Marvel Studios' release schedule, Whedon noted that the series had "a little more freedom" and were "able to do a little bit more" with the species going into the fourth season, including the potential of introducing some of the "classic" Inhumans.[171]Marvel's Inhumans, a television series centered on Black Bolt and other members of the Inhuman Royal Family, was announced in November 2016 to air on ABC in September 2017.[172] It is not intended to be a spin-off of Agents of S.H.I.E.L.D.[173]

The fourth season explores the concept of Life Model Decoys (LMDs),[57] which were first referenced in The Avengers,[174] and introduces the character Ghost Rider to the MCU.[8] On why the series waited to begin exploring LMDs, Jed Whedon said that the series previously did not want to explore the concept before the release of Avengers: Age of Ultron, which sees the introductions of Ultron and Vision in a similar manner to LMDs.[175] On introducing Ghost Rider, Whedon said that "with Doctor Strange coming out this year, the Marvel [Cinematic] Universe is moving into new waters," referring to the exploration of magic. "We felt that this was obviously a great character that we'd love to have on our show that we feel fits with that shift."[176] The season also continues storylines from the second season of Agent Carter, with the reveal that the Momentum Energy Labs group is a successor to the Isodyne Energy company, with both companies connected by the parent company Roxxon, a mainstay of the MCU.[177] In August 2017, Emily VanCamp said that discussions had taken place for her to reprise her role of Sharon Carter for the series, but there were conflicts with her starring role on the series Revenge.[178]

Agents of S.H.I.E.L.D. airs in the United States on ABC,[70] in 720phigh definition and 5.1 surround sound,[193] despite delivering the episodes to ABC in 1080p.[138] The first season aired on Tuesdays at 8pm EST for the first season,[194] and starting with the second season, the series aired on Tuesdays at 9pm EST,[195] before moving to the 10pm time slot on Tuesdays for the fourth season.[196] For its fifth season, the series will air on Fridays at 9pm EST.[191]

Agents of S.H.I.E.L.D. has been licensed in 155 countries and territories:[197]CTV holds the broadcast rights for Canada;[198]Channel 4 aired the series in the United Kingdom for the first two seasons, before it moved to E4 for the third;[199] in Australia, the series aired on Seven Network for the first two seasons,[200] before moving to Fox8 starting with the third;[201] and in New Zealand, the show airs on TV2.[202]MyNetworkTV was awarded the series' syndication rights, and began broadcasting it in September 2016.[203]

The second and third seasons of the series were broadcast in two blocks each, with a season of Agent Carter airing in between. Bell explained that this decision was made following the challenge of producing 22 episodes for the first season to be aired over 36–40 weeks, which meant having repeats and "losing momentum". Instead, Agent Carter took up much of that gap in a row, leaving the back half of Agents of S.H.I.E.L.D.'s season to run uninterrupted.[22] This format allowed the producers and writers to approach each season in two parts, each with distinct stories connected by carried-over elements.[204] Ahead of the fourth season, Tancharoen explained, "For the past two seasons, we've been able to break our season down into two little mini-seasons because of the airdate schedule. This upcoming season, our airdate schedule is a little different, so we're breaking it into three pods. Story wise, the development of that has made our lives easier, to break it down in that way."[76]

Regarding if they would break the fifth season into pods again as with season four, Bell said, "A 22-episode arc is a lot for people to hold onto. By breaking it up into either smaller arcs or different pods, by introducing a set of antagonists and putting them down, or moving from space to space, our experience has been that it’s something the viewers enjoy, and it makes it a little easier to digest when you’re telling some of these stories." Whedon also noted it would depend on how the season would be "broken up in terms of airing. If everything is running back-to-back, it feels weird to start calling it different things... We will try to have it in bite-sized chunks."[205] The season began airing its episodes on December 1, 2017,[9] once Inhumans has aired its eight episodes,[206] with the intent for all 22 episodes to air mostly uninterrupted;[206] a short hiatus was taken for the airing of the 2018 Winter Olympics.[207] The season ultimately was formed by two pod story arcs.[208]

Social media accounts for the series were set up in January 2013, months before ABC officially ordered it, "a rarity for a pilot."[209] By May 17, 2013, Agents of S.H.I.E.L.D. was the top new show of the television season in terms of social media activity, with the series' official Twitter account having over 46,000 followers and its official Facebook page having close to half a million likes.[209] Many cast and crew members "live tweet" each episode, with J. August Richards noting that this brings instant feedback from viewers, and allows the crew to "watch the audience take that journey" in real time.[210]

For the final six episodes of the first season, Marvel began the "Marvel's Agents of S.H.I.E.L.D.: The Art of Level Seven" initiative, in which a different image was released each Thursday before a new episode, depicting a first look at a key event from the upcoming episode. Bell stated that the initiative was a way to tie the series back to its comics roots, and was thought of at the beginning of the first season. The production team tried to pair specific artists to the teaser posters based on their previous work and how it connected to the themes and emotion of the intended episode.[211] For the second season, the series returned as "The Art of Evolution", with an image for each of the final twelve episodes of the season.[212] For season five, Marvel revived their marketing art program, with "Marvel's Agents of S.H.I.E.L.D.: The Road to 100", with five posters, one for each season of the series, representing "key pivotal moments of each season" to commemorate the series reaching 100 episodes.[213]

A five-part web series titled Agents of S.H.I.E.L.D.: Double Agent, also sponsored by Lexus, was released from March 4 to May 6, 2015 on ABC.com. The web series follows a newly hired Agents of S.H.I.E.L.D. production assistant, who acts as a double agent for the "Mastermind", portrayed by Stan Lee. Cast and crew members from the series, such as Gregg, also appear, with viewers having the ability to vote in an online poll after each episode to guess where the double agent would go in the next episode; votes entered viewers in a drawing to win prizes from the set of Agents of S.H.I.E.L.D.[217][218]Double Agent was nominated for Outstanding Digital Series at the 27th Producers Guild Awards.[219] Another Lexus-sponsored five-part web series, Agents of S.H.I.E.L.D.: Academy, released from March 9 to May 4, 2016. In Academy, three Agents of S.H.I.E.L.D. fans compete to play an agent in that series. Members of the Agents of S.H.I.E.L.D. cast also appear.[220] All three fans ultimately made cameo appearances in the third-season finale.[221]

The series has been promoted with various subtitles at different times, including: Agents of S.H.I.E.L.D.: Uprising in season one, leading up to the Winter Soldier crossover;[222]Agents of S.H.I.E.L.D.: Fallen Agent for the end of the third season;[53]Agents of S.H.I.E.L.D.: Ghost Rider for the first "pod" of season four;[223] and Agents of S.H.I.E.L.D.: LMD for the second "pod" of season four.[224] The third "pod" of season four was known as Agents of Hydra.[225]

The complete first season was first released on Blu-ray and DVD on September 9, 2014,[179] with the complete second season released on September 18, 2015, as an Amazon.com exclusive.[183][226] On Netflix in the United States, the first season became available for streaming on November 20, 2014,[182] the second season on June 11, 2015,[186] the third season on June 16, 2016,[189] and the fourth season on June 15, 2017.[190]

In the United States, the premiere episode of Agents of S.H.I.E.L.D. earned a 4.7/14 rating in the 18- to 49-year-old demographic, with 12.12 million total viewers,[227] making it the biggest network drama debut in four years.[246] Though the series debuted to strong ratings against its competition, NCIS, its ratings declined considerably over the following two months, though it remained Tuesday's top show among men 18–49, and overall was the No. 3 show among upscale young adults behind Modern Family and The Big Bang Theory. It also enjoyed DVR recordings that, according to TV Guide, were "through the roof".[247]

In March 2016, Alisha Grauso of Forbes discussed the series and its ratings, describing the show as having "never quite been the ratings hit for ABC that the network had hoped it would be...It's hard enough to write a film script that fits within the continuity of the larger Marvel Cinematic Universe, even harder to do it with a full-length TV season that must act as connective tissue to the larger world while still being its own thing." Grauso opined that the series' ratings may improve if it either focused on trying to be the best series it could be (with fewer connections to the films, like the Marvel-Netflix shows) or on just being "support and tie-in to the world of the Avengers". Grauso concluded, "The end result for either scenario is that, hopefully, ratings move up and stay up. In the first case, fans might be lost by the disconnect from the MCU, but a stronger storyline and more consistent writing would bring them and new fans back. In the second scenario, fans would tune in every week for fear of missing out on a bit of story that's important to the larger world."[248][249]

Agents of S.H.I.E.L.D. saw the season five episodes "A Life Spent", "A Life Earned", "All the Comforts of Home", and "The Real Deal" earn series low ratings of 0.5/2 each in the 18- to 49-year-old demographic,[250][251][252][253] with "A Life Earned" also having the lowest initial viewer number for the series with 1.84 million.[251]

For the first season, the review aggregator website Rotten Tomatoes reported an 85% approval rating, with an average rating of 7.8 out of 10 based on 48 reviews. The website's consensus reads, "Agents of S.H.I.E.L.D. is sure to please comic book fans, but the strong ensemble and brisk pacing help to make this better-than-average superhero show accessible to non-fanboys as well."[230]Metacritic, which uses a weighted average, assigned a "generally favorable" score of 74 based on 33 reviews.[231] The second season scored a 96% approval rating on Rotten Tomatoes, with an average score of 7.6 out of 10 based on 24 reviews, and the consensus "Agents of S.H.I.E.L.D. relaxes into itself during its sophomore season, mitigating the show's growing pains by focusing on characters while amping up narrative thrills."[235]

The third season has a 100% approval rating on Rotten Tomatoes, with an average score of 8.3 out of 10 based on 15 reviews. The website's consensus reads, "Still evolving in its third season, Agents of S.H.I.E.L.D. further hits its stride with a blend of thrills, humor, and heart."[239] The fourth season also has a 94% approval rating on Rotten Tomatoes, with an average score of 7.6 out of 10 based on 18 reviews, and the consensus reads "Agents of S.H.I.E.L.D. explores darker territory in its fourth season with the thrilling introduction of Ghost Rider, setting up an action-packed new chapter of Marvel's edgier mythologies."[243]

The way that the series is affected by the events of Captain America: The Winter Soldier has been called "miraculous",[254][255] with Terri Schwartz at Zap2it writing "the fact that the movie so influenced the show is game-changing in terms of how the mediums of film and television can be interwoven",[254] while Mary McNamara of the Los Angeles Times stated that Agents of S.H.I.E.L.D. "faces a future of perpetual re-invention, and that puts it in the exhilarating first car of television's roller-coaster ride toward possible world domination."[255] The fact that the series also depicts the rebuilding of S.H.I.E.L.D. in the MCU has also been highlighted, with Merrill Barr, reviewing "Beginning of the End" for Forbes, saying "what Marvel's daring to say with this season finale is 'everything we do matters, and you need to pay attention to all of it.'"[256]

The series' introduction of the Inhumans was seen by Oliver Sava of The A.V. Club as making Agents of S.H.I.E.L.D. an essential part of the MCU and Marvel Studios' plans, with the connections between the series and the films previously having always been reactive on the series' behalf, with "stuff" happening in the films, and Agents of S.H.I.E.L.D. dealing with the fallout of it. However, the series would now be "making things happen, and these events will clearly impact the future of the MCU".[257] Barr wrote that the series "does a most excellent job of standing on its own two feet in a way we've never seen it do before. Come the final frame [of the second season finale], all anyone—Marvel fan or otherwise—will be asking is when season three begins."[258]

The third season's paralleling of themes from Captain America: Civil War was called "topical and relevant" and "downright eerie" by The A.V. Club's Alex McCown and Screen Crush's Kevin Fitzpatrick. McCown compared the series' approach to setting up "a world distrustful of superpowers" to the real life events surrounding Cliven Bundy and Donald Trump's 2016 presidential campaign, and said that "S.H.I.E.L.D. is taking full advantage of its medium in order to tell the story the upcoming Captain America film can't: A full and fraught exploration of the need to protect freedom and privacy, even for those with extraordinary abilities." Fitzpatrick added that this "topical bent...made for a great angle to build up that world mentality without feeling particularly subservient to the movies."[259][260]

Ahead of the fourth season, Collider.com's Kayti Burt opined that Agents of S.H.I.E.L.D. is "the X-Men TV show you should be watching". Burt noted that the X-Men film franchise was expanding to television with the series Legion, but that S.H.I.E.L.D. already served that purpose well, highlighting the similarities between the X-Men and the Inhumans, both creations of Stan Lee and Jack Kirby during the 1960s consisting of a large group of super-powered people who "are our neighbors and our friends ... both heroes and villains", and face "the same fears and prejudices" from the wider community. Burt felt that the similarities between S.H.I.E.L.D.'s Inhumans and the X-Men became "particularly pointed" in the third season with the Hive storyline, which had a lot in common with the film X-Men: Apocalypse that was released around the same time; Burt was of the opinion that S.H.I.E.L.D. executed the storyline "much better" than the film did. Other similarities Burt discussed were the series' diverse and ensemble cast, its take on the mutant cure storyline, the parallels between Daisy Johnson's second season arc and the introduction of Rogue in the first X-Men film, and its social and political commentary. With the latter, Burt also discussed the similarities between the Watchdogs and Donald Trump, calling it "not very subtle, but social commentary doesn't have to be. I appreciate that Agents of S.H.I.E.L.D. is attempting to comment on the current socio-political state of the country in a way that many of the other superhero TV shows don't even attempt to do. It's perhaps the show's most X-Men-like quality." Concluding, Burt said that though the X-Men characters cannot appear in the MCU due to 20th Century Fox holding the rights, "we still get to enjoy many of the themes prominent in the X-Men universe through S.H.I.E.L.D."[261]

Additionally, Marc N. Kleinheinz at Screen Rant discussed how the series "continues to resist a status quo", from the destruction and rebuilding of S.H.I.E.L.D., to the fallout from the Sokovia Accords. He noted that a major driving force behind the changes was the MCU films, with the series being forced "to constantly adapt to a changing narrative landscape that it has absolutely no control over." He also believed that the series was obligated to adapt various Marvel characters to screen which would not be appearing in films, such as Daisy Johnson, Mockingbird, and Ghost Rider. However, Kleinheinz felt that this mindset also came from within the series crew rather than just from Marvel, saying, "there's also the storytelling modus operandi that showrunners Jed Whedon and Maurissa Tancharoen have very obviously demonstrated during their four-year tenure. It seems that constantly staking out new ground from season to season is just as much a personal predilection as it is, possibly, a corporate mandate."[262]

During the Agents of Hydra pod in the fourth season, Collider.com's Evan Valentine noted how "[o]ne of the prevalent themes of this latter half of Agents of S.H.I.E.L.D.'s fourth season has been its jabs at the current Trump administration... When all’s said and done, whether you support or disavow the current administration and what it’s done with its time in office, does this commentary work here? Sure it does... We need to be able to laugh at what’s going on in the world, regardless of whether we agree or disagree, but S.H.I.E.L.D. has managed to throw in some biting commentary this season."[263]

By April 2015, Marvel was developing a spin-off series of Agents of S.H.I.E.L.D. The series, which was being developed by Bell and writer Paul Zbyszewski, would be based on storylines occurring at the end of the second season of Agents of S.H.I.E.L.D., and would receive its own pilot rather than a backdoor pilot.[304] Though Palicki and Blood were reportedly in final discussions to headline the potential new series,[305] ABC passed on the project by May 7, 2015, when they announced their series renewals and cancellations, and new series pickups.[306]

In August 2015, the spin-off series received new life as a reworked series, titled Marvel's Most Wanted, with a pilot order.[307] Bell and Zbyszewski once again developed the series, while also serving as co-writers of the pilot, executive producers, and showrunners, with Jeph Loeb also attached as executive producer.[308] The series would still focus on Morse and Hunter, with Palicki and Blood both attached, and was described as "a new take focusing on the same duo and their continuing adventures."[307]

Bell and Zbyszewski worked together on the characters' storyline for the third season of Agents of S.H.I.E.L.D., preparing them to move over to the spin-off,[309] with Bell explaining that it would set up Most Wanted by defining exactly who the characters are, such as Hunter and his lack of loyalty to S.H.I.E.L.D. and to ideologies—"nothing specific about the show, it's just who Hunter is."[310] In March 2016, Bell stated that while Hunter and Morse are "on S.H.I.E.L.D., we want to take advantage of who they are, and give the audience as much of their relationship with one another, and with other people, as possible. We are aware that there is a potential imminent end, and so they won't be neglected."[311]

Hunter and Morse are written off the series in the episode "Parting Shot", both leaving S.H.I.E.L.D., as Palicki and Blood "physically had to go leave to shoot the pilot....they had to stop being on S.H.I.E.L.D. and get ready for the pilot and then shoot the pilot and all of that, so it didn't make sense for us to have all these episodes with them and then not have them in two or three episodes, and then go, 'Oh, we were just over here,' and then come back and go away again." On whether they could return to the series at some point, Bell said, "I can't answer that, but I can say it would be kind of cheating to make Mack cry like that [in the episode] only to buy it back—not that we haven't brought characters back from the dead. We want to earn stuff."[102] In May 2016, the spin-off series was passed on by ABC once again.[312]

A six-part web series, Marvel's Agents of S.H.I.E.L.D.: Slingshot, was revealed on December 6, 2016, to debut on ABC.com on December 13, 2016. It follows Elena "Yo-Yo" Rodriguez on a secret mission, shortly before the start of season four, with Cordova-Buckley reprising her role.[224] Gregg, Jason O'Mara, Simmons, Bennet, Wen, De Caestecker and Henstridge all reprise their roles in the series as Coulson, Jeffrey Mace, Mack, Johnson, May, Fitz and Simmons, respectively.[313]

At the 2014 San Diego Comic Con International, Marvel Comics announced an ongoing series titled S.H.I.E.L.D., to be set in the mainstream Marvel Universe and written by Mark Waid, beginning December 2014. Featuring art by a rotating group of artists including Carlos Pacheco, Alan Davis, and Chris Sprouse, the series is led by Agent Phil Coulson, and sees the canonical introduction of the characters Melinda May, Jemma Simmons, and Leo Fitz—who originated from the television series—to the Marvel comics universe, who Waid noted would be given "the Marvel Universe spin." Waid described the series as "done-in-one. Coulson and his team have a mission, and if we need someone for a mission, everyone in the Marvel Universe is available as a potential Agent."[314][315][316] Waid added that though the comic does not share events with the television series, it will maintain the characters' relationships and personalities.[317]Marc Guggenheim relaunched the comic as Agents of S.H.I.E.L.D. for Marvel Comics' All-New, All-Different Marvel line,[318] and introduced the television series' character Grant Ward to the Marvel comic universe in May 2016.[319]

In September 2015, it was announced that Phil Coulson, Daisy Johnson / Quake, Deathlok, Melinda May, Bobbi Morse, Lincoln Campbell, Sif, Raina and Gordon would appear in the Marvel: Future Fight mobile role-playing video game. Their inclusion in the game was done to promote the start of the third season, as well as to allow Marvel to "extend storylines and build on backstories to engage fans in a brand-new experience," according to Marvel Games creative director Bill Rosemann.[320] In March 2016, de Caestecker and Henstridge reprised their roles as Fitz and Simmons, respectively, in the episode "Lizards", of the animated series Ultimate Spider-Man vs the Sinister 6.[321] Also in the month, Agents of S.H.I.E.L.D.downloadable content was revealed for Lego Marvel's Avengers.[322] The content consisted of a mission based "on the events leading up to the season two finale", which involved facing Jiaying and Daisy in Afterlife while rescuing agents,[323] as well as going up against Gordon and Cal Johnson who have occupied the S.H.I.E.L.D. Helicarrier.[322][323] The content includes the playable characters Daisy Johnson, Leo Fitz, Agent Koenig, Melinda May, Bobbi Morse, Jemma Simmons, Cal Johnson / Mr. Hyde, Deathlok, Gordon, Grant Ward, Jiaying, Lincoln, and Raina, as well as the airplane 'The Bus'.[322] Ming-Na Wen reprised her role as Melinda May to provide new dialogue for the content.[323]